Research On Resource Optimization Technique Of Wireless Communication Based On HARQ Protocols

Multi-hop relay technology and MIMO technology can enhance the system capacity and the transmission reliability by introducing space diversity to resist fading and improve spectrum utilization.In order to further improve the information reliability of MIMO and multi-hop relay technology.Hybrid Automatic retransmission re Quest(HARQ)is presented and investigated.This dissertation aims at improving the transmission reliability and efficiency by optimization of MIMO-HARQ pre-encoding and multi-hop relay network combined with HARQ technology with respect to key parameters such as transmission energy,number of retransmission and optimal interruption position in multi-hop cooperation transmission.The main work and innovations are as follows:Through the investigation of HARQ retransmission and MIMO precoding strategy,we propose a MIMO-HARQ encoding algorithm considering fairness and a MIMO-HARQ precoding strategy based on HARQ partial data retransmission,to enhance the reliability and the spectrum efficiency of HARQ retransmission in MIMO communication.The proposed precoding strategy with consideration of fairness can avoid the number of retransmission and further improve the efficiency of resource utilization;partial retransmission precoding strategy employs the orthogonality of the MIMO antenna signal to operate both the retransmission of information and transmission of new information and so as to increase the spectrum efficiency.Two MIMO-HARQ precoding designs have low complexity,high resource utilization and superior practical value.We discuss and optimize the energy efficiency of multi-hop HARQ on Rayleigh channel.Specifically,By introducing a generalized expression of asymptotic fading distributions,the optimal solutions are derived in explicit forms that facilitate the analysis on the performance of multihop networks in a more efficient way,we first derive the specific expression of energy efficiency in multi-hop HARQ networks based on the fact that frame error rate(FER)is a linear model.This expression jointly considers coding scheme in PHY layer and frame length in MAC layer,as well as transmission energy and circuit energy consumption.Then,taking this expression into account,we jointly optimize the frame length and transmission energy.At the end,considering the constraint of total power in multi-hop HARQ,we propose an optimization strategy that combines the frame length and transmission energy.The accuracy of the model and the effectiveness of the optimization strategy is checked by the simulation results,and the parameters affecting the energy efficiency are discussed according to the simulation results.Based on the spectrum efficiency maximization,the optimization strategies of transmission power and transmission rate in multi-hop networks with different retransmission mechanisms are designed.According to multiple hops network end-to-end interrupt probability model for different types of HARQ transmission strategy analyses and compares the spectrum efficiency,design the corresponding to each retransmission strategy under multiple hops network transmission speed and power joint optimization method,is given according to different channel state,transmission distance and power Numerical results demonstrate that the proposed strategy outperforms the conventional separate optimization strategies including the strategies that optimize either power or rate.Also,it is found performance improvement increases with the increase in link unbalance.By introducing Nakagami-m fading channel,we study the network resource optimization in multi-hop HARQ.For mobile terminal based mobile ad-hoc networks,such as vehicular networks,multi-agent networks,in which nodes can move autonomously in a small range,we compare different methods with respect to the performance of diversity gain and coding gain.Thus we provide a reference for designing optimization for multi-hop HARQ networks in small-scale fading channel.The analysis results show that the introduction of retransmission time improves the flexibility of transmission strategy design,and the combination optimization of retransmission time,transmission distance and transmission power can effectively improve the end-to-end performance of time-delay limited multi-hop HARQ network.At last,we present a general numerical approach to evaluate the outage probability and study resource optimization technology in a more realistic scenario.Specifically,considering composite fading channel that combines path loss,large scale fading caused by the shadow effect and small-scale fading caused by multipath fading,we approximate multi-hop HARQ networks and derive the end-to-end outage probability.To minimize outage probability,we propose a strategy that optimizes power jointly allocation and deployment of relay position.We analyze and discuss the computational accuracy of the approximation,computation complexity and scope of application in simulation.The simulation results show that the approximation method and optimization algorithm can be adopted in a large range of applications and achieve exceptional performance of multi-hop HARQ network resource allocation in composite fading channel at a low computation complexity.